pub mod camera;
pub mod figure;
pub mod simple;
pub mod terrain;

use self::{
    camera::{Camera, CameraMode},
    figure::FigureMgr,
    terrain::Terrain,
};
use crate::{
    anim::character::SkeletonAttr,
    audio::{music::MusicMgr, sfx::SfxMgr, AudioFrontend},
    render::{
        create_pp_mesh, create_skybox_mesh, Consts, Globals, Light, Model, PostProcessLocals,
        PostProcessPipeline, Renderer, Shadow, SkyboxLocals, SkyboxPipeline,
    },
    window::Event,
};
use common::{
    comp,
    state::State,
    terrain::{BlockKind, TerrainChunk},
    vol::ReadVol,
};
use specs::{Entity as EcsEntity, Join, WorldExt};
use vek::*;

// TODO: Don't hard-code this.
const CURSOR_PAN_SCALE: f32 = 0.005;

const MAX_LIGHT_COUNT: usize = 32;
const MAX_SHADOW_COUNT: usize = 24;
const LIGHT_DIST_RADIUS: f32 = 64.0; // The distance beyond which lights may not emit light from their origin
const SHADOW_DIST_RADIUS: f32 = 8.0;
const SHADOW_MAX_DIST: f32 = 96.0; // The distance beyond which shadows may not be visible

struct Skybox {
    model: Model<SkyboxPipeline>,
    locals: Consts<SkyboxLocals>,
}

struct PostProcess {
    model: Model<PostProcessPipeline>,
    locals: Consts<PostProcessLocals>,
}

pub struct Scene {
    globals: Consts<Globals>,
    lights: Consts<Light>,
    shadows: Consts<Shadow>,
    camera: Camera,

    skybox: Skybox,
    postprocess: PostProcess,
    terrain: Terrain<TerrainChunk>,
    loaded_distance: f32,
    select_pos: Option<Vec3<i32>>,

    figure_mgr: FigureMgr,
    sfx_mgr: SfxMgr,
    music_mgr: MusicMgr,
}

pub struct SceneData<'a> {
    pub state: &'a State,
    pub player_entity: specs::Entity,
    pub loaded_distance: f32,
    pub view_distance: u32,
    pub tick: u64,
    pub thread_pool: &'a uvth::ThreadPool,
}

impl Scene {
    /// Create a new `Scene` with default parameters.
    pub fn new(renderer: &mut Renderer) -> Self {
        let resolution = renderer.get_resolution().map(|e| e as f32);

        Self {
            globals: renderer.create_consts(&[Globals::default()]).unwrap(),
            lights: renderer
                .create_consts(&[Light::default(); MAX_LIGHT_COUNT])
                .unwrap(),
            shadows: renderer
                .create_consts(&[Shadow::default(); MAX_SHADOW_COUNT])
                .unwrap(),
            camera: Camera::new(resolution.x / resolution.y, CameraMode::ThirdPerson),

            skybox: Skybox {
                model: renderer.create_model(&create_skybox_mesh()).unwrap(),
                locals: renderer.create_consts(&[SkyboxLocals::default()]).unwrap(),
            },
            postprocess: PostProcess {
                model: renderer.create_model(&create_pp_mesh()).unwrap(),
                locals: renderer
                    .create_consts(&[PostProcessLocals::default()])
                    .unwrap(),
            },
            terrain: Terrain::new(renderer),
            loaded_distance: 0.0,
            select_pos: None,

            figure_mgr: FigureMgr::new(),
            sfx_mgr: SfxMgr::new(),
            music_mgr: MusicMgr::new(),
        }
    }

    /// Get a reference to the scene's globals.
    pub fn globals(&self) -> &Consts<Globals> { &self.globals }

    /// Get a reference to the scene's camera.
    pub fn camera(&self) -> &Camera { &self.camera }

    /// Get a reference to the scene's terrain.
    pub fn terrain(&self) -> &Terrain<TerrainChunk> { &self.terrain }

    /// Get a reference to the scene's figure manager.
    pub fn figure_mgr(&self) -> &FigureMgr { &self.figure_mgr }

    /// Get a mutable reference to the scene's camera.
    pub fn camera_mut(&mut self) -> &mut Camera { &mut self.camera }

    /// Set the block position that the player is interacting with
    pub fn set_select_pos(&mut self, pos: Option<Vec3<i32>>) { self.select_pos = pos; }

    /// Handle an incoming user input event (e.g.: cursor moved, key pressed,
    /// window closed).
    ///
    /// If the event is handled, return true.
    pub fn handle_input_event(&mut self, event: Event) -> bool {
        match event {
            // When the window is resized, change the camera's aspect ratio
            Event::Resize(dims) => {
                self.camera.set_aspect_ratio(dims.x as f32 / dims.y as f32);
                true
            },
            // Panning the cursor makes the camera rotate
            Event::CursorPan(delta) => {
                self.camera.rotate_by(Vec3::from(delta) * CURSOR_PAN_SCALE);
                true
            },
            // Zoom the camera when a zoom event occurs
            Event::Zoom(delta) => {
                self.camera
                    .zoom_switch(delta * (0.05 + self.camera.get_distance() * 0.01));
                true
            },
            // All other events are unhandled
            _ => false,
        }
    }

    /// Maintain data such as GPU constant buffers, models, etc. To be called
    /// once per tick.
    pub fn maintain(
        &mut self,
        renderer: &mut Renderer,
        audio: &mut AudioFrontend,
        scene_data: &SceneData,
        gamma: f32,
    ) {
        // Get player position.
        let player_pos = scene_data
            .state
            .ecs()
            .read_storage::<comp::Pos>()
            .get(scene_data.player_entity)
            .map_or(Vec3::zero(), |pos| pos.0);

        let player_rolling = scene_data
            .state
            .ecs()
            .read_storage::<comp::CharacterState>()
            .get(scene_data.player_entity)
            .map_or(false, |cs| cs.action.is_roll());

        let player_scale = match scene_data
            .state
            .ecs()
            .read_storage::<comp::Body>()
            .get(scene_data.player_entity)
        {
            Some(comp::Body::Humanoid(body)) => SkeletonAttr::calculate_scale(body),
            _ => 1_f32,
        };

        // Alter camera position to match player.
        let tilt = self.camera.get_orientation().y;
        let dist = self.camera.get_distance();

        let up = match self.camera.get_mode() {
            CameraMode::FirstPerson => {
                if player_rolling {
                    player_scale * 0.8_f32
                } else {
                    player_scale * 1.6_f32
                }
            },
            CameraMode::ThirdPerson => 1.2,
        };

        self.camera.set_focus_pos(
            player_pos + Vec3::unit_z() * (up + dist * 0.15 - tilt.min(0.0) * dist * 0.75),
        );

        // Tick camera for interpolation.
        self.camera.update(scene_data.state.get_time());

        // Compute camera matrices.
        self.camera.compute_dependents(&*scene_data.state.terrain());
        let camera::Dependents {
            view_mat,
            proj_mat,
            cam_pos,
        } = self.camera.dependents();

        // Update chunk loaded distance smoothly for nice shader fog
        self.loaded_distance =
            (0.98 * self.loaded_distance + 0.02 * scene_data.loaded_distance).max(0.01);

        // Update light constants
        let mut lights = (
            &scene_data.state.ecs().read_storage::<comp::Pos>(),
            scene_data.state.ecs().read_storage::<comp::Ori>().maybe(),
            scene_data
                .state
                .ecs()
                .read_storage::<crate::ecs::comp::Interpolated>()
                .maybe(),
            &scene_data.state.ecs().read_storage::<comp::LightEmitter>(),
        )
            .join()
            .filter(|(pos, _, _, _)| {
                (pos.0.distance_squared(player_pos) as f32)
                    < self.loaded_distance.powf(2.0) + LIGHT_DIST_RADIUS
            })
            .map(|(pos, ori, interpolated, light_emitter)| {
                // Use interpolated values if they are available
                let (pos, ori) =
                    interpolated.map_or((pos.0, ori.map(|o| o.0)), |i| (i.pos, Some(i.ori)));
                let rot = {
                    if let Some(o) = ori {
                        Mat3::rotation_z(-o.x.atan2(o.y))
                    } else {
                        Mat3::identity()
                    }
                };
                Light::new(
                    pos + (rot * light_emitter.offset),
                    light_emitter.col,
                    light_emitter.strength,
                )
            })
            .collect::<Vec<_>>();
        lights.sort_by_key(|light| light.get_pos().distance_squared(player_pos) as i32);
        lights.truncate(MAX_LIGHT_COUNT);
        renderer
            .update_consts(&mut self.lights, &lights)
            .expect("Failed to update light constants");

        // Update shadow constants
        let mut shadows = (
            &scene_data.state.ecs().read_storage::<comp::Pos>(),
            scene_data
                .state
                .ecs()
                .read_storage::<crate::ecs::comp::Interpolated>()
                .maybe(),
            scene_data.state.ecs().read_storage::<comp::Scale>().maybe(),
            &scene_data.state.ecs().read_storage::<comp::Body>(),
            &scene_data.state.ecs().read_storage::<comp::Stats>(),
        )
            .join()
            .filter(|(_, _, _, _, stats)| !stats.is_dead)
            .filter(|(pos, _, _, _, _)| {
                (pos.0.distance_squared(player_pos) as f32)
                    < (self.loaded_distance.min(SHADOW_MAX_DIST) + SHADOW_DIST_RADIUS).powf(2.0)
            })
            .map(|(pos, interpolated, scale, _, _)| {
                Shadow::new(
                    // Use interpolated values pos if it is available
                    interpolated.map_or(pos.0, |i| i.pos),
                    scale.map_or(1.0, |s| s.0),
                )
            })
            .collect::<Vec<_>>();
        shadows.sort_by_key(|shadow| shadow.get_pos().distance_squared(player_pos) as i32);
        shadows.truncate(MAX_SHADOW_COUNT);
        renderer
            .update_consts(&mut self.shadows, &shadows)
            .expect("Failed to update light constants");

        // Update global constants.
        renderer
            .update_consts(&mut self.globals, &[Globals::new(
                view_mat,
                proj_mat,
                cam_pos,
                self.camera.get_focus_pos(),
                self.loaded_distance,
                scene_data.state.get_time_of_day(),
                scene_data.state.get_time(),
                renderer.get_resolution(),
                lights.len(),
                shadows.len(),
                scene_data
                    .state
                    .terrain()
                    .get(cam_pos.map(|e| e.floor() as i32))
                    .map(|b| b.kind())
                    .unwrap_or(BlockKind::Air),
                self.select_pos,
                gamma,
            )])
            .expect("Failed to update global constants");

        // Maintain the terrain.
        self.terrain.maintain(
            renderer,
            &scene_data,
            self.camera.get_focus_pos(),
            self.loaded_distance,
            view_mat,
            proj_mat,
        );

        // Maintain the figures.
        self.figure_mgr.maintain(renderer, scene_data, &self.camera);

        // Remove unused figures.
        self.figure_mgr.clean(scene_data.tick);

        // Maintain audio
        self.sfx_mgr
            .maintain(audio, scene_data.state, scene_data.player_entity);
        self.music_mgr.maintain(audio, scene_data.state);
    }

    /// Render the scene using the provided `Renderer`.
    pub fn render(
        &mut self,
        renderer: &mut Renderer,
        state: &State,
        player_entity: EcsEntity,
        tick: u64,
    ) {
        // Render terrain and figures.
        self.figure_mgr.render(
            renderer,
            state,
            player_entity,
            tick,
            &self.globals,
            &self.lights,
            &self.shadows,
            &self.camera,
        );
        self.terrain.render(
            renderer,
            &self.globals,
            &self.lights,
            &self.shadows,
            self.camera.get_focus_pos(),
        );

        // Render the skybox.
        renderer.render_skybox(&self.skybox.model, &self.globals, &self.skybox.locals);

        self.terrain.render_translucent(
            renderer,
            &self.globals,
            &self.lights,
            &self.shadows,
            self.camera.get_focus_pos(),
        );

        renderer.render_post_process(
            &self.postprocess.model,
            &self.globals,
            &self.postprocess.locals,
        );
    }
}